"warming effects when relatively thin, cirrus clouds have been implicated as a potential partial cause of global warming. Scientists have speculated that global warming could cause high thin cloud cover to increase, thereby increasing temperatures and humidity. This, in turn, would increase the cirrus cloud cover, effectively creating a positive feedback circuit. A prediction of this hypothesis is that the cirrus would move higher as the temperatures rose, increasing the volume of air underneath the clouds and the amount of infrared radiation reflected back down to earth. In addition, the hypothesis suggests that the increase in temperature would tend to"
"Cirrocumulus cloud Cirrocumulus is one of the three main genus-types of high-altitude tropospheric clouds, the other two being cirrus and cirrostratus. They usually occur at an altitude of to . Like lower altitude cumuliform and stratocumuliform clouds, cirrocumulus signifies convection. Unlike other high-altitude-tropospheric clouds like cirrus and cirrostratus, cirrocumulus includes a small amount of liquid water droplets, although these are in a supercooled state. Ice crystals are the predominant component, and typically, the ice crystals cause the supercooled water drops in the cloud to rapidly freeze, transforming the cirrocumulus into cirrostratus. This process can also produce precipitation in the form"
"this may also be seen in conjunction with showers and thunderstorms). If it is seen after rain it usually means improving weather. Cirrocumulus cloud Cirrocumulus is one of the three main genus-types of high-altitude tropospheric clouds, the other two being cirrus and cirrostratus. They usually occur at an altitude of to . Like lower altitude cumuliform and stratocumuliform clouds, cirrocumulus signifies convection. Unlike other high-altitude-tropospheric clouds like cirrus and cirrostratus, cirrocumulus includes a small amount of liquid water droplets, although these are in a supercooled state. Ice crystals are the predominant component, and typically, the ice crystals cause the supercooled"
"useful for weather forecasting as cumulonimbus clouds are related to thunderstorms and heavy rain whereas cirrus clouds are not directly associated with precipitation. The liquid water content of a cloud varies significantly depending on the type of clouds present in the atmosphere at a given location. The classification of the cloud is highly related to the liquid water content as well as the origin of the cloud. The combination of these two allows a forecaster to more readily predict the types of conditions that will be in an area based on the types of clouds that are forming or have"
"into cirrus because as the water vapor continues to deposit on the ice crystals, they eventually begin to fall, destroying the upward convection. The cloud then dissipates into cirrus. Cirrocumulus clouds come in four species: ""stratiformis"", ""lenticularis"", ""castellanus"", and ""floccus"". They are iridescent when the constituent supercooled water droplets are all about the same size. Cirrostratus clouds can appear as a milky sheen in the sky or as a striated sheet. They are sometimes similar to altostratus and are distinguishable from the latter because the sun or moon is always clearly visible through transparent cirrostratus, in contrast to altostratus which"
"and halos. Cirrus is known to raise the temperature of the air beneath the main cloud layer by an average of 10 °C (18 °F). When the individual filaments become so extensive that they are virtually indistinguishable from one another, they form a sheet of high cloud called cirrostratus. Convection at high altitudes can produce another high-based genus called cirrocumulus, a pattern of small cloud tufts that contain droplets of supercooled water. Cirrus clouds form on other planets, including Mars, Jupiter, Saturn, Uranus, and possibly Neptune. They have even been seen on Titan, one of Saturn's moons. Some of these"
"of instability or convective activity. High clouds form at altitudes of in the polar regions, in the temperate regions and in the tropics. All cirriform clouds are classified as high and thus constitute a single genus ""cirrus"" (Ci). Stratocumuliform and stratiform clouds in the high altitude range carry the prefix ""cirro-"", yielding the respective genus names ""cirrocumulus"" (Cc) and ""cirrostratus"" (Cs). When limited-resolution satellite images of high clouds are analysed without supporting data from direct human observations, it becomes impossible to distinguish between individual forms or genus types, which are then collectively identified as ""high-type"" (or informally as ""cirrus-type"" even"
"then dissipates into cirrus. Cirrocumulus clouds come in four species which are common to all three genus-types that have limited-convective or stratocumuliform characteristics: ""stratiformis"", ""lenticularis"", ""castellanus"", and ""floccus"". They are iridescent when the constituent supercooled water droplets are all about the same size. Altocumulus clouds are a mid-level cloud that forms from high to in polar areas, in temperate areas, and in tropical areas. They can have precipitation and are commonly composed of a mixture of ice crystals, supercooled water droplets, and water droplets in temperate latitudes. However, the liquid water concentration was almost always significantly greater than the concentration"
"thus they have been referred to as ""one of the most beautiful clouds"". This occurs because they reflect the unscattered rays of light from the early morning or evening sun, and those rays are yellow, orange, red, and sometimes purple Cirrocumulus usually only forms in patches. If it forms in patches with cirrus or cirrostratus and the clouds spread across the sky, it usually means rain in 8–10 hours (can be more if front is slow moving). If there are only small patches of cirrocumulus and perhaps some wisps of cirrus, it usually means a continuation of good weather (although"
"though not all high clouds are of the cirrus form or genus). Non-vertical clouds in the middle level are prefixed by ""alto-"", yielding the genus names ""altocumulus"" (Ac) for stratocumuliform types and ""altostratus"" (As) for stratiform types. These clouds can form as low as above surface at any latitude, but may be based as high as near the poles, at mid latitudes, and in the tropics. As with high clouds, the main genus types are easily identified by the human eye, but it is not possible to distinguish between them using satellite photography. Without the support of human observations, these"
"are often classified separately as clouds of vertical development, especially when their tops are high enough to be composed of super-cooled water droplets or ice crystals. The altitudes of high-étage clouds like cirrus vary considerably with latitude. In the polar regions, they are at their lowest, with a minimum altitude of only to a maximum of . In tropical regions, they are at their highest, ranging in altitude from about to around . In temperate regions, they range in altitude from to —a variation in contrast to low-étage clouds, which do not appreciably change altitude with latitude. There are three"
"moisture in the upper atmosphere. Cirrostratus clouds sometimes signal the approach of a warm front if they form after cirrus and spread from one area across the sky, and thus may be signs that precipitation might follow in the next 12 to 24 hours or as soon as 6–8 hours if the front is fast moving. If the cirrostratus is broken fibratus, it can mean that the front is weak and that stratus rather than nimbostratus will be the precipitating cloud (meaning drizzle or snow grains instead of moderate rain or snow). Cumulus humilis or stratocumulus clouds are often found"
"If the air becomes more unstable, the cloud tends to grow vertically into the species ""mediocris"", then ""congestus"", the tallest cumulus species which is the same type that the International Civil Aviation Organization refers to as 'towering cumulus'. With highly unstable atmospheric conditions, large cumulus may continue to grow into cumulonimbus ""calvus"" (essentially a very tall congestus cloud that produces thunder), then ultimately into the species ""capillatus"" when supercooled water droplets at the top of the cloud turn into ice crystals giving it a cirriform appearance. All cloud varieties fall into one of two main groups. One group identifies the"
"main genera in the family of high clouds: cirrus, cirrocumulus, and cirrostratus. Cirrostratus clouds commonly produce halos because they are composed almost entirely of ice crystals. Cirrocumulus and cirrostratus are sometimes informally referred to as ""cirriform clouds"" because of their frequent association with cirrus. They are given the prefix ""cirro-"", but this refers more to their altitude range than their physical structure. Cirrocumulus in its pure form is actually a high cumuliform genus, and cirrostratus is stratiform, like altostratus and lower based sheet clouds. Cirrocumulus clouds form in sheets or patches and do not cast shadows. They commonly appear in"
"of a virga consisting of ice or snow. Thus cirrocumulus clouds are usually short-lived. They usually only form as part of a short-lived transitional phase within an area of cirrus clouds and can also form briefly as a result of the breaking up of part of a cumulonimbus anvil. Properly, the term cirrocumulus refers to each cloud, but is typically also used to refer to an entire patch of cirrocumulus. When used in this way, each cirrocumulus element is referred to as a ""cloudlet"". Cirrocumulus is a cloud of the ""stratocumuliform"" physical category that shows both stratiform and cumuliform characteristics"
"be common to more than one genus or species. Of the stratiform group, high-level cirrostratus comprises two species. Cirrostratus ""nebulosus"" has a rather diffuse appearance lacking in structural detail. Cirrostratus ""fibratus"" is a species made of semi-merged filaments that are transitional to or from cirrus. Mid-level altostratus and multi-level nimbostratus always have a flat or diffuse appearance and are therefore not subdivided into species. Low stratus is of the species nebulosus except when broken up into ragged sheets of stratus fractus (see below). Cirriform clouds have three non-convective species that can form in mostly ""stable"" airmass conditions. Cirrus fibratus comprise"
"describes the occasional arrangements of cloud structures into particular patterns that are discernible by a surface-based observer (cloud fields usually being visible only from a significant altitude above the formations). These varieties are not always present with the genera and species with which they are otherwise associated, but only appear when atmospheric conditions favor their formation. ""Intortus"" and ""vertebratus"" varieties occur on occasion with cirrus fibratus. They are respectively filaments twisted into irregular shapes, and those that are arranged in fishbone patterns, usually by uneven wind currents that favor the formation of these varieties. The variety ""radiatus"" is associated with"
"filaments that may be straight, wavy, or occasionally twisted by non-convective wind shear. The species ""uncinus"" is similar but has upturned hooks at the ends. Cirrus ""spissatus"" appear as opaque patches that can show light grey shading. Stratocumuliform genus-types (cirrocumulus, altocumulus, and stratocumulus) that appear in mostly stable air have two species each. The ""stratiformis"" species normally occur in extensive sheets or in smaller patches where there is only minimal convective activity. Clouds of the ""lenticularis"" species tend to have lens-like shapes tapered at the ends. They are most commonly seen as orographic mountain-wave clouds, but can occur anywhere in"
"cloud types comprise cirrus, cirrocumulus, and cirrostratus. The middle étage extends from above surface at any latitude as high as near the poles, at mid latitudes, and in the tropics. Altocumulus and Altostratus are the main cloud types found in the middle levels of the troposphere. The low étage is found from surface up to at all latitudes. Principal cloud types found in the low levels of the troposphere include stratocumulus, stratus, and small fair weather cumulus. Several additional types usually form in the low or middle étages but typically extend into all three altitude levels as clouds with significant"
"moderate to heavy precipitation. The remaining cumuliform (cumulus) and stratocumuliform (stratocumulus, altocumulus, and cirrocumulus) clouds have the least in common with nimbostratus. Nimbostratus cloud Nimbostratus is a stratiform genus formerly classified as ""Family C” low-level, but now considered by the World Meteorological Organization (WMO) to be a ""middle-"" or ""multi-level"" stratus type.. Although it is usually a low-based cloud, it actually forms most commonly in the middle level of the troposphere and then spreads vertically into the low and high levels. This change in classification would once have made it a ""Family D"" cloud, but this style of letter-based family"
"to in polar areas, in temperate areas, and in tropical areas. The high-level cloud, cirrocumulus, is a stratocumuliform cloud of limited convection. The other clouds in this level are cirrus and cirrostratus. High clouds form in high latitudes, in temperate latitudes, and in low, tropical latitudes. Cumulonimbus clouds, like cumulus congestus, extend vertically rather than remaining confined to one level. Cirrocumulus clouds form in patches and cannot cast shadows. They commonly appear in regular, rippling patterns or in rows of clouds with clear areas between. Cirrocumulus are, like other members of the cumuliform and stratocumuliform categories, formed via convective processes."
"from a high viewpoint or from a plane. Cirrus clouds only form glories when the constituent ice crystals are aspherical, and researchers suggest that the ice crystals must be between 0.009 millimeters and 0.015 millimeters in length. Cirrus clouds are one of three different genera of high-étage (high-level) clouds. High-étage clouds form at and above in temperate regions. The other two genera, cirrocumulus and cirrostratus, are also high clouds. In the intermediate range, from to in temperate regions, are the mid-étage clouds. They comprise two or three genera depending on the system of height classification being used: altostratus, altocumulus, and,"
"known as veering, and in the southern hemisphere a shift from northwest to southwest (anticlockwise, backing). Normally, cold fronts can be marked by these characteristics: <nowiki>*provided there is sufficient moisture.</nowiki> If the cold front is highly unstable, cumulonimbus clouds producing thunderstorms commonly form along the front. Anvil cirrus clouds may spread a considerable distance downwind from the thunderstorms. The other cloud types associated with a cold front depend on atmospheric conditions such as air mass stability and wind shear. As the front approaches, middle-étage gives way to altostratus and low-level stratocumulus with intermittent light precipitation if the warm airmass being"
"cloud rows of a particular type that appear to converge at the horizon. It is sometimes seen with the fibratus and uncinus species of cirrus, the stratiformis species of altocumulus and stratocumulus, the mediocris and sometimes humilis species of cumulus, and with the genus altostratus. Another variety, ""duplicatus"" (closely spaced layers of the same type, one above the other), is sometimes found with cirrus of both the fibratus and uncinus species, and with altocumulus and stratocumulus of the species stratiformis and lenticularis. The variety ""undulatus"" (having a wavy undulating base) can occur with any clouds of the species stratiformis or"
"the clouds include cirrus castellanus, cirrocumulus castellanus, altocumulus castellanus and stratocumulus castellanus. Sometimes cumulus castellanus are referred to, but the type is not recognised by the France's national meteorological service Météo-France, or by the American Meteorological Society and World Meteorological Organisation. Those clouds some would classify as cumulus castellanus typically do not have a common base and are not arranged in a line, thus differing to some extent from the more universally-recognised castellanus types. Some scientists also think that the ""castellanus"" should be a full cloud genus, and not just a cloud species. The Federal Aviation Administration ""implicitly"" considers a"
"Significant growth of these patches indicates high-altitude instability and can signal the approach of poorer weather. The ice crystals in the bottoms of cirrocumulus clouds tend to be in the form of hexagonal cylinders. They are not solid, but instead tend to have stepped funnels coming in from the ends. Towards the top of the cloud, these crystals have a tendency to clump together. These clouds do not last long, and they tend to change into cirrus because as the water vapor continues to deposit on the ice crystals, they eventually begin to fall, destroying the upward convection. The cloud"
"white when sunlit, and is dark underneath. A single pattern-based variety, Cumulus radiatus, is sometime seen when the individual clouds are arranged into parallel rows. The resulting formations are known as ""cloud streets"" and are aligned nearly parallel to the wind. Cumulus mediocris may have precipitation-based features like virga, and may form Cumulus praecipitato clouds. The pannus supplementary feature is sometimes seen with precipitating Cumulus mediocris, but in this case the C7 reporting code normally used with to identify pannus is usually superseded by C2, since there is significant vertical development. ""Pileus"" (cap cloud), ""velum"" (apron), ""arcus"" (roll or shelf"
"A wide variety of weather can be found along an occluded front, with thunderstorms possible, but usually their passage is associated with a drying of the air mass. Occluded fronts usually form around mature low-pressure areas. Precipitation may occur on celestial bodies other than Earth. When it gets cold, Mars has precipitation that most likely takes the form of ice needles, rather than rain or snow. Convective rain, or showery precipitation, occurs from convective clouds, e.g., cumulonimbus or cumulus congestus. It falls as showers with rapidly changing intensity. Convective precipitation falls over a certain area for a relatively short time,"
"it cools, any water vapor that is present will condense and form extensive cloud cover. The first clouds that indicate an approaching warm front tend to be mostly high cirrus at first, changing to cirrostratus as the front approaches. However, if cirrocumulus also appears, there is greater airmass instability approaching ahead of the front. When these high clouds progressively invade the sky and the barometric pressure begins to fall, precipitation associated with the disturbance is likely about 6 to 8 hours away. A thickening and lowering of these high clouds into middle-étage altostratus or altocumulus is a good sign the"
"counting subvisible cirrus clouds. Clouds play multiple critical roles in the climate system. In particular, being bright objects in the visible part of the solar spectrum, they efficiently reflect light to space and thus contribute to the cooling of the planet. Cloud cover thus plays an important role in the energetic balance of the atmosphere and a variation of it is a consequence of and to the climate change expected by recent studies. Cloud cover values only vary by 0.03 from year to year, whereas the local, day to day variability in cloud amount typically rises to 0.3 over the"
"Castellanus A castellanus (or castellatus) (from latin ""castellanus"", castle) is a cloud that displays at least in its upper part cumuliform protuberances having the shape of turrets that give a crenellated aspect. Some of these turrets are higher than they are wide; they have a common base and seem to be arranged in a line. The castellanus characteristic is particularly obvious when the clouds are observed from the side (i.e., from a vantage point on a line perpendicular to the line of orientation). It is a cloud species attached to the cloud genera cirrus, cirrocumulus, altocumulus and stratocumulus. Species of"
"and lesser types. High-level clouds form at altitudes of 5 to 12 kilometers. All cirriform clouds are classified as high-level and therefore constitute a single cloud genus cirrus. Stratiform and stratocumuliform clouds in the high level of the troposphere have the prefix ""cirro-"" added to their names yielding the genera cirrostratus and cirrocumulus. Similar clouds found in the middle level (altitude range 2 to 7 kilometers) carry the prefix ""alto-"" resulting in the genus names altostratus and altocumulus. Low level clouds have no height-related prefixes, so stratiform and stratocumuliform clouds based around 2 kilometres or lower are known simply as"
"be very dense, and the exact appearance of the cloud can vary from one formation to another. In the winter, precipitation often follows behind these clouds; however, they are not a precipitation-producing cloud. Cirrostratus nebulosus Cirrostratus nebulosus is a species of high-level cirrostratus cloud. The name ""cirrostratus nebulosus"" is derived from Latin, the adjective ""nebulosus"" meaning ""full of vapor, foggy, cloudy, dark"". Cirrostratus nebulosus is one of the two most common forms that cirrostratus often takes, with the other being cirrostratus fibratus. The nebulosus species is featureless and uniform, while the fibratus species has a fibrous appearance. Cirrostratus nebulosus are"